Diamond Color Enhancement
The oldest technique to enhance a diamond’s color is to coat it. Not as common as it once was, this sophisticated process uses ultra-thin layers of chemicals or plastics to enhance a diamond’s color. Today, most coated diamonds are easily detectable under magnification. Irradiation induces a permanent color change throughout the entire stone. The post–World War II atomic age saw an influx of artificially irradiated diamonds.
HPHT stands for a High Pressure, High Temperature, a laboratory process which can be used to change the color in some gem diamonds. In the 1990s, scientists began to experiment with ways to modify diamond color using this technique. HPHT treatment can change the color of certain diamonds, making them colorless, pink, blue, green, yellowish green, or yellow.
Diamond Clarity Enhancement
Two techniques for improving a diamond’s clarity are laser drilling and fracture filling. Both of these clarity enhancements are easily detected with magnification and suitable lighting. Laser drilling is used to remove small, dark inclusions. The laser bores a small hole into the diamond’s interior and burns away the inclusion, leaving behind a tiny drill hole.
Fracture filling hides white areas which are called “feathers.” A glass-like substance is injected into the fracture to make it less visible, improving the stone’s clarity by one or even two diamond quality grades. But because it is not stable to all routine cleaning and repair techniques, the technique has been quite controversial.
